Grapefruit seed extract (GSE), also known as citrus seed extract, is a liquid

extract An extract is a substance made by extracting a part of a raw material, often by using a solvent such as ethanol, oil or water. Extracts may be sold as tinctures, absolutes or in powder form. The aromatic principles of many spices, nuts ...

derived from the

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...

s, pulp, and white membranes of

grapefruit The grapefruit (''Citrus'' × ''paradisi'') is a subtropical citrus tree known for its relatively large, sour to semi-sweet, somewhat bitter fruit. The interior flesh is segmented and varies in color from pale yellow to dark pink. Grapefruit i ...

. GSE is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with

glycerin Glycerol (), also called glycerine in British English and glycerin in American English, is a simple triol compound. It is a colorless, odorless, viscous liquid that is sweet-tasting and non-toxic. The glycerol backbone is found in lipids know ...

. Commercially available GSEs sold to consumers are made from the seed, pulp, and glycerin blended together. GSE is sold as a

dietary supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in orde ...

and is used in

cosmetics Cosmetics are constituted mixtures of chemical compounds derived from either natural sources, or synthetically created ones. Cosmetics have various purposes. Those designed for personal care and skin care can be used to cleanse or protec ...

Grapefruit history

The grapefruit is a subtropical

citrus ''Citrus'' is a genus of flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as oranges, lemons, grapefruits, pomelos, and limes. The genus ''Citrus'' is nati ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

grown for its

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...

which was originally named the "

forbidden fruit Forbidden fruit is a name given to the fruit growing in the Garden of Eden which God commands mankind not to eat. In the biblical story, Adam and Eve eat the fruit from the tree of the knowledge of good and evil and are exiled from Eden. A ...

" of

Barbados Barbados is an island country in the Lesser Antilles of the West Indies, in the Caribbean region of the Americas, and the most easterly of the Caribbean Islands. It occupies an area of and has a population of about 287,000 (2019 estimate ...

. The fruit was first documented in 1750 by Rev.

Griffith Hughes The Reverend Griffith Hughes (1707 – c.1758), FRS, was a Welsh naturalist, clergyman, and author. Hughes wrote ''The Natural History of Barbados,'' which included the first description of the grapefruit (also known as "The Forbidden Fruit"). ...

when describing specimens from Barbados.Michael Quinion
World Wide Words: Questions & Answers; Grapefruit
2009. All parts of the fruit can be used. The fruit is mainly consumed for its tangy

juice Juice is a drink made from the extraction or pressing of the natural liquid contained in fruit and vegetables. It can also refer to liquids that are flavored with concentrate or other biological food sources, such as meat or seafood, such ...

. The peel can be processed into

aromatherapy Aromatherapy is based on the usage of aromatic materials including essential oils and other aroma compounds, with claims for improving psychological and physical well-being. It is offered as a complementary therapy or as a form of alternative ...

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) & lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

s and is also a source of

dietary fiber Dietary fiber (in British English fibre) or roughage is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibers are diverse in chemical composition, and can be grouped generally by th ...

. The seed and pulp, as

byproduct A by-product or byproduct is a secondary product derived from a production process, manufacturing process or chemical reaction; it is not the primary product or service being produced. A by-product can be useful and marketable or it can be consid ...

s of the juice industry, are retrieved for GSE processing or sold as cattle feed.

Efficacy

Despite

claims Claim may refer to: * Claim (legal) * Claim of Right Act 1689 * Claims-based identity * Claim (philosophy) * Land claim * A ''main contention'', see conclusion of law * Patent claim * The assertion of a proposition; see Douglas N. Walton ...

that GSE has

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ...

effects, there is no scientific evidence that GSE has such properties. Some evidence indicates that the suspected antimicrobial activity of GSE was due to the contamination or adulteration of commercial GSE preparations with synthetic antimicrobials or

preservatives A preservative is a substance or a chemical that is added to products such as food products, beverages, pharmaceutical drugs, paints, biological samples, cosmetics, wood, and many other products to prevent decomposition by microbial growth or b ...

. These chemicals were not present in grapefruit seed extracts prepared in the

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physici ...

, and GSE preparations without the contaminants were found to possess no detectable antimicrobial effect. Although citrus seed extract is sold in health food markets, there is no good evidence for any antimicrobial activity.

Phytochemicals

Analysis shows the

phytochemical Phytochemicals are chemical compounds produced by plants, generally to help them resist fungi, bacteria and plant virus infections, and also consumption by insects and other animals. The name comes . Some phytochemicals have been used as poison ...

s of the seed extract and pulp are flavonoids,

ascorbic acid Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) a ...

(

vitamin C Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) a ...

tocopherol Tocopherols (; TCP) are a class of organic chemical compounds (more precisely, various methylated phenols), many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rat ...

citric acid Citric acid is an organic compound with the chemical formula HOC(CO2H)(CH2CO2H)2. It is a colorless weak organic acid. It occurs naturally in citrus fruits. In biochemistry, it is an intermediate in the citric acid cycle, which occurs in t ...

, limonoids, sterols, and

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...

Preparations

GSE is prepared by grinding the grapefruit seed and juiceless pulp, then mixing with glycerin. Commercially available GSE is made from the seed, pulp, glycerin, and synthetic preservatives all blended together.

Health claims and safety concerns

Although various health claims for using GSE are marketed in the

industry, there is no

scientific evidence Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. "Discussions about empirical e ...

from high-quality

clinical research Clinical research is a branch of healthcare science that determines the safety and effectiveness ( efficacy) of medications, devices, diagnostic products and treatment regimens intended for human use. These may be used for prevention, treat ...

that it has any health effects, as of 2018. Phytochemicals in grapefruit seeds, particularly furanocoumarins and flavonoids, may cause adverse effects on health resulting from

grapefruit–drug interactions Some fruit juices and fruits can interact with numerous drugs, in many cases causing adverse effects. The effect is most studied with grapefruit and grapefruit juice, but similar effects have been observed with certain other citrus fruits. ...

that influence the intended therapeutic effects of some 85

prescription drug A prescription drug (also prescription medication or prescription medicine) is a pharmaceutical drug that legally requires a medical prescription to be dispensed. In contrast, over-the-counter drugs can be obtained without a prescription. The rea ...

s. The main safety concern about GSE is inhibition of the

liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

cytochrome P450 Cytochromes P450 (CYPs) are a superfamily of enzymes containing heme as a cofactor that functions as monooxygenases. In mammals, these proteins oxidize steroids, fatty acids, and xenobiotics, and are important for the clearance of various compo ...

, which controls liver metabolism of drugs; consequently, its inhibition by GSE unpredictably increases the blood concentrations of prescribed drugs.

References

{{reflist, 30em Dietary supplements Grapefruit Seeds